Rep. Nancy Pelosi of California, the House minority leader, led 130 fellow Democrats in filing a friend-of-the-court brief Thursday challenging the 1996 Defense of Marriage Act, The San Francisco Chronicle reported.

The brief argues that Republicans defending the law, which denies all federal benefits to married same-sex couples, do not represent the full House. The document was filed in connection with Massachusetts cases that are before the U.S. Court of Appeals for the 1st Circuit, in Boston. The cases are the first of a dozen challenges to the law nationwide to reach the federal appellate level.

The Democrats’ brief challenges the decision by House Republican leaders to hire former Solicitor General Paul Clement to defend the statute after the Justice Department decided in February it could no longer do so on constitutional grounds (see Main Justice’s earlier report).

Evan Wolfson, founder and president of Freedom to Marry, called the Democrats’ brief “a tremendously powerful statement to the courts and the country” that shows “how much the political center of gravity has shifted on the marriage question,” The Chronicle reported. “Fifteen years ago, people were falling over themselves to sign on to DOMA.”

The Senate Judiciary Committee is expected to vote next week on a bill by Sen. Dianne Feinstein (D-Calif.) to repeal the law.

The court filing pits Democrats against Republicans in the legal arena, as well as in the court of public opinion. It is likely that the DOMA issue will reach the U.S. Supreme Court, and it is certain to be an issue in next year’s elections.